Key Points for Study Chapter 8: Basic Concepts of Chemical Bonding I. Common Misconceptions • A triple bond is not necessarily three times as strong as a single bond (cannot say the bond strength in a triple would be 3 x bond strength in a single – check out Table 8.4 for bond enthalpy), although the bond length is shorter when a multiple bond is formed. • Count the number of valence electrons correctly in order to get the correct Lewis structure. • Understand that formal charge does not represent real charge on atoms. • The only place the ↔ arrow is used is for resonance; it is not to indicate equilibrium at this time. • The exceptions to the octet rule are almost as common as the examples of substances that obey it. II. Useful tips 1. Learn how to look for a pattern to synthesize your ideas and understanding: e.g., lattice energy and bond enthalpy (difference and similarity) – eqully helpful is then to identify exceptions. You can go across chapters, e.g., to chapter 7, see the concepts of ionization energy (equation 7.3) and electron affinity. Any pattern to learn? 2. Learn how to use chemical equations to represent your concepts and vice versa : e.g., Equation 8.3 for lattice energy and Cl 2 (g) Æ 2Cl (g) for bond enthalpy. III. Kek Points 1. Chemical bond is formed when atoms or ions are strongly attracted to one another (via electron sharing by or electron transferring between atoms). 2. Lewis Symbols is a pictorial understanding/presentation of where the electrons are in an atom. The number of valence electrons available for bonding are indicated by unpaired dots – Lewis symbols . 3. The Octet Rule : Atoms tend to gain, lose or share electrons until they are surrounded by eight valence electrons -- known as the octet rule (a critical concept for chemical bonding, implied that a noble gas electron configuration is stable --- a yard stick or bench mark for chemical reactivity). (1) Octet consists of full s and p subshells. (2) s 2 p 6 is a noble gas configuration. (3) Assumed that an atom is stable when surrounded by eight electrons (four electron pairs).

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